I'm on Cox Cable in Tucson and I have an Scientific Atlanta Explorer 8300 HDDVR. Unfortunately Cox has pretty poor HD offerings with only CBS of the big broadcast networks in HD. I know the others, ABC, Fox, NBC broadcast locally and when I had DirecTV I could pick then up with an antenna.
I can't quite figure a way to connect the antenna to the cable receiver/DVR. I could put in a splitter but I'm not sure how I'd switch between the cable and the antenna.